Robert Greenwood

Erythrocytes as Oral Delivery Systems for Human Insulin

The use of different forms of human red blood cells as oral carrier systems for human insulin in vivo was the subject of this investigation. Male Wistar rats were made diabetic by a single intraperitoneal injection of streptozocin (100 mg/kg). Three days after the injection, rats were found diabetic as evidenced by elevated fasted blood glucose concentration (200 mg/dl or higher). Rats received orally one of the following (100 U, 2 ml): an insulin solution, a ghosts-insulin suspension, a vesicles-insulin suspension, a liposomes-ghosts-insulin suspension, or a liposomes-vesicles-insulin suspension. Free carrier suspensions or sodium chloride solution (0.9%) were also given orally as controls. Blood glucose concentration was determined just before administration and at 1, 2, 3, 4, 5, 6, and 7 hr post administration. The results show that all treatment groups, except liposomes-ghosts-insulin, were significantly different statistically from their respective controls (i.e., the free carriers).

Human Insulin Binding to Erythrocyte-Membrane

AbstractThe binding of human insulin to erythrocyte membrane in the form of ghosts, vesicles (ultrasonicated ghosts), lipid-coated-ghosts or lipid-coated-vesicles was the subject of this study. Insulin was found to associate with ghosts in two mechanisms, by encapsulation and adsorption on the surface. Insulin binding reached equilibrium with a much faster rate with ghosts than the other carriers, due to these two mechanisms. The findings from this study suggest that the use of these carrier-insulin systems may be of value in the delivery of insulin in the treatment of diabetes.

Intraduodenal Administration of Biocarrier-Insulin Systems

AbstractSuccessful oral administration of insulin for systemic therapeutic effects has long been a major pharmaceutical challenge. Intraduodenal administration of insulin to rats, free or in a form of carrier-insulin, was the subject of this study. Several erythrocyte-membrane carrier systems (ghosts, vesicles, liposomes-ghosts, and liposomes-vesicles) were tested. Insulin (100 U) was incubated with each of the carriers at 37°C for 24 hr. The carrier-insulin system, insulin solution, sodium chloride solution, or carrier-free insulin was then introduced into the duodenum of anesthetized male Wistar diabetic rats. Blood samples were collected from the tail at different time intervals and then analyzed for glucose content using an o-toluidine method. There was no significant difference in blood glucose concentrations among the control groups. However, ghosts-insulin, vesicles-insulin, and liposomes-vesicles-insulin all showed a statistically significant difference in lowering blood glucose levels when compar...

Human insulin absorption from the intestine in diabetic rats

AbstractThe ability of human insulin to produce hypoglycemia in streptozocin-diabetic rats (average weight 500 g) was investigated. A simple solution of human insulin (insulin in hypotonic buffer solution) was administered intraduodenally. Rats received a dose of insulin of either 200 U/kg, 400 U/kg, or 600 U/kg. The hypoglycemic response was most significant when 600 U/kg solution of insulin was administered. The 200 U/kg dose was of two forms; one form was a solution of insulin with a concentration of 25 U/ml, 4 ml, and the other was a solution of insulin with a concentration of 50 U/ml, 2 ml. The dose of 25 U/ml, 4 ml produced a more significant hypoglycemic response than that of 50 U/ml, 2 ml. Carrier-insulin systems were also introduced intraduodenally in streptozocin-diabetic rats. The results indicate that the carrier systems without insulin had glucogenic effect. Despite this glucogenic effect, carrier-insulin systems at 200 U/kg dose were as effective as that of 600 U/kg of insulin solution. We c...

A brief report on some physiological parameters of streptozocin-diabetic rat

Several biological changes occur when streptozocin is given to experimental animals. The rat streptozocin (STZ) model is extensively used in diabetic experiments. In this brief report, the main physiological characteristics of rats injected with streptozocin are presented. These characteristics are manifested by weight loss, organ weight reduction, serum glucose elevation, decrease in serum insulin level, and other enzyme and hormonal changes. A collection of these parameters may be helpful in establishing a database to describe this model.

Incorporation of Simethicone into Syrupy or Clear Base Liquid Orals

AbstractThe objective of this project was to incorporate simethicone in a syrupy or clear base liquid oral.Best results were obtained when a commercially available emulsion concentrate was stabilized with Carbopol® resins. The use of 0.2% neutralized Carbopol® resin in combination with glycerin and propylene glycol produced a very stable formulation which did not show any separation or creaming for the duration of the studies.

Diffusion Profile of Human Insulin Through Polycarbonate Membrane

AbstractThe aim of this study was to investigate the diffusion of human insulin through polycarbonate membrane, a common mechanical support used in cell culture studies. The pore size of the polycarbonate membranes, the presence of collagen on the surface of the membrane, and the pH of the medium affected the diffusion of insulin through the membrane. Minimum diffusion occured at pH near the isoelectric point of insulin (5.3). The larger the pore size of the polycarbonate membrane the higher the amount diffused. The transfer rate of insulin was slower when membranes were coated with collagen.